Method and device for the checking banknotes

ABSTRACT

The present invention relates to a method and an apparatus for checking bank notes, in which data from at least two different measurings of the bank notes to be checked are evaluated. The invention starts out from a checking of bank notes, with which data from at least two different measurings of bank notes to be checked are evaluated, a first property of the bank note to be checked being derived from the data of at least one first measuring, at least one second property of the bank note to be checked being derived from the data of at least one second measuring, a correlation between first and at least second property for the same places on the bank note to be checked being determined, and the first property being derived once again, for the places of the bank note to be checked, for which a correlation between first and at least second property has been determined, an altered derivation of the first property from the data of the at least first measuring being performed.

The present invention relates to a method and an apparatus for checkingbank notes, with which data from at least two different measurings ofthe bank notes to be checked are evaluated.

The checking of bank notes usually is carried out with the help ofsensors, which capture data that represent certain properties of banknotes. The data of each sensor normally are evaluated independently ofthe data coming from the other sensors.

From EP 1 172 773 A1 an apparatus and a method for checking theauthenticity of documents is known, in which the data of an opticalsensor are used for determining the position of a magnetic securitythread. The position of the security thread determined by the opticalsensor is used for selectively actuating a magnetic sensor, so that thismagnetic sensor can readout the coding contained in the security threadexactly at the position of the security thread.

The known methods and apparatuses for checking bank notes do not renderany statements on how the checking of bank notes by means of at leasttwo different measurings of the bank notes to be checked can beimproved, when at least one of the different measurings containsinformation or data that can lead to an incorrect checking.

Therefore, it is the problem of the present invention to specify amethod and an apparatus for checking bank notes, with which data from atleast two different measurings of the bank notes to be checked areevaluated, an incorrect checking on the basis of the evaluation of thedata of the at least two different measurings being avoided.

According to the present invention this problem is solved by thefeatures of the claims 1 and 9.

The invention starts out from a checking of bank notes, with which datafrom at least two different measurings of bank notes to be checked areevaluated, a first property of the bank note to be checked being derivedfrom the data of at least one first measuring, at least one secondproperty of the bank note to be checked being derived from the data ofat least one second measuring, a correlation between first and at leastsecond property for the same places on the bank note to be checked beingdetermined, and the first property being derived once again, for theplaces of the bank note to be checked, for which a correlation betweenfirst and at least second property has been determined, an alteredderivation of the first property from the data of the at least firstmeasuring being performed. In connection with the present inventioncorrelation shall not solely mean the formation of a correlationfunction, but every local or not-local arithmetical or logicalconnection of data or of properties derived from this data.

The invention thus in particular has the advantage, that due to thealtered derivation disturbing information in the data evaluated for thepurpose of checking bank notes can be suppressed, as a result of whichthe quality and plausibility of the checking is improved. This allows areliable evaluation of the features and/or properties of the bank notesto be checked, whereas with only one measuring or with two isolatedmeasurings of the features and/or properties there can occur problems,e.g. because the captured features and/or properties are notunambiguous.

Further advantages of the present invention appear from the dependentclaims as well as the following description of one embodiment withreference to Figures.

FIG. 1 shows a schematic representation of a basic structure of anapparatus for the checking of bank notes, and

FIG. 2 shows a schematic representation of a checking of a bank note.

FIG. 1 shows a schematic representation of a basic structure of anapparatus 10 for checking bank notes.

The apparatus 10 for checking is formed as a bank note processingmachine and has an input pocket 20 for feeding bank notes 21 to beprocessed, into which a singler 22 engages. The singler 22 seizes one ofthe bank notes 21 to be processed and transfers the individual bank noteto a transport system 23, which transports the individual bank notethrough a sensor arrangement 30.

In this sensor arrangement 30 there are at least two different sensors31, 32, 33, for example a first optical sensor 31, which captures lightreflected by the bank note, a second acoustic sensor 33, which capturesin particular transmitted ultrasonic signals coming from the bank note,and a third optical sensor 32, which captures light transmitted by thebank note. The sensors 31, 32, 33 perform a measuring for the purpose ofchecking bank notes, during which they capture features and/orproperties of each individual bank note and generate respective data.For this purpose the sensors 31, 32, 33 detect the bank notes with agiven resolution, from which results a pixel size with which the banknotes are scanned and captured.

From the captured pixels of each bank note the sensors 31, 32, 33 and/ora control device 35 generate data, which represent each place on thesurface of the respective bank note. The generation of the data by thesensors 31, 32, 33 e.g. can be performed for only one side of the banknotes, i.e. for one of the surfaces of the bank notes, however, likewisethe two surfaces can be captured and the respective data are madeavailable thereby. Preferably, the sides or surfaces of the bank noteseach are completely scanned and then the respective data for thecomplete side or surface are generated.

From the data generated by the sensors 31, 32, 33 properties arederived, which are relevant for checking bank notes. These propertiescan relate to, for example, authenticity, kind (currency, denomination),state (damage, soiling) etc. of the respective bank note. The respectiveproperties can be derived, for example, from the data of one or aplurality of sensors 31, 32, 33.

In the control device 35 the data of the sensors 31, 32, 33 are comparedto reference data stored within the control device 35, which allow therecognition of authentic or counterfeited bank notes and/or bank notessuspected of forgery, the kind of bank notes, state of bank notes etc.

On the basis of the checking of the respective bank notes performed bythe control device 35 switches 24, 26 disposed in the transport system23 are actuated in order to e.g. store bank notes being in a good statein an output pocket 25, whereas bank notes which are in a poor state canbe stored in an output pocket 27 or can be transferred to furtherprocessing via the transport system 23.

FIG. 2 schematically shows a checking of a bank note.

With the check a first property of the bank note is to be determined,e.g. the state of the bank note with respect to the degree of soiling ofthe bank note. Soiling here in particular means spots, impermissblyadded inscriptions etc.

For this purpose, for example, from the data of the first, opticalsensor 31, which e.g. captures light of a certain wavelength reflectedby the bank note, the control device 35 derives those areas or places onthe surface of the bank note, the data of which indicate a soiling. InFIG. 2 the soiled areas or places are marked by dark areas in arepresentation 131 of the bank note.

Furthermore, at least one second property of the bank note isdetermined, e.g. the state of the bank note with respect to the degreeof damage or destructions of the bank note. Damage or destructions herein particular shall mean holes, tears, defective spots, dog-ears,adhesive tapes etc.

For this purpose, for example, from the data of the second, opticalsensor 32, which e.g. captures light of a certain wavelength transmittedby the bank note, the control device 35 derives those areas or places onthe surface of the bank note, the data of which indicate a damage ordestruction. In FIG. 2 the damaged or destroyed areas or places aremarked by black areas 1 to 4 in a representation 132 of the bank note.The area 1 indicates a hole in the bank note, the areas 2 and 3 indicatetears in the bank note and the areas 4 indicate defective spots ordog-ears.

For checking or proving the second property of the bank note (here:damage or destructions) derived from the data of the second, opticalsensor 32, the data of the third, acoustic sensor 33 can be used. Forthis purpose the data of the acoustic sensor 33 additionally can beevaluated in different ways by the control device 35.

When the data of the acoustic sensor 33, which for example detectstransmitted ultrasound, are examined as to places with high signalstrength, the places on the bank note having holes 1′, tears 2′ anddefective spots 4′, as shown in a representation 133, can be derived bythe control device 35.

In a step 40 for the purpose of checking or proving the derived holes,tears and defective spots, the holes 1, 1′, tears 2, 3, 2′ and defectivespots 4, 4′ determined before (representation 132 and 133) are compared,as shown in a representation 41. It is determined thereby that e.g. thetear 3 detected by the optical sensor 32 has not been detected by theacoustic sensor 33. Therefore, in a next step 45 the control device 35calculates a representation 42, in which only the hole 1, the tear 2 andthe defective spots 4 are contained.

From the data of the acoustic sensor 33, which for example detectstransmitted ultrasound, further conclusions can be drawn as to the stateof the bank note. When the control device 35 examines the data as toplaces that have nearly no signal strength, as shown in therepresentation 133′, the places 5 on the bank note having increasedthickness or wall thickness can be derived by the control device 35.Such places 5 indicate, for example, the presence of dog-ears. When thedata of the acoustic sensor 33 are examined as to places with reducedsignal strength, the places 6 on the bank note can be derived by thecontrol device 35 that, for example, indicate the presence of anadhesive tape, as shown in representation 133″

The information about dog-ears 5 and adhesive tapes 6 in a further step50 is combined with information about the hole 1, the tear 2 and thedefective spots 4 by the control device 35 as to form a representation51, which contains all determined and proved damage or destructions ofthe bank note.

In a further step 60 a mask 61 is formed by the control device 35, whichcontains the spatial distribution of the damage or destructions 1, 2, 4,5, 6, i. e. the places on the bank note to be checked showing therespective damage or destructions.

In a next step 70 the mask 61 is put on the soiled areas or places ofthe bank note by the control device 35, which during the derivationprocess of the first property of the bank note to be checked have beenderived from the data of the first sensor 31 and are shown in therepresentation 131. The result is a representation 71, from whichappears the spatial or local correlation of the first property (soiling)with the second property (damage or destruction).

For the final evaluation of the soiling of the bank note, the firstproperty characterizing the soiling is derived once again from the data(dark spots in representation 131) of the first sensor 31 by the controldevice 35, the derivation process from the data being altered.

In such an altered derivation process it may be provided that the dataof the optical sensor 31, which locally correlate with the at leastsecond property (damage or destruction), are not taken into account. Inthis case a last step 80 of the processing performed by the controldevice 35 results in a representation 81 showing the distribution ofsoiling on the bank note to be checked, which is taken into account whenthe first property (soiling) is derived once again. Therefore, places onthe bank note to be checked, which by mistake may be evaluated assoiling (holes 1″, tears 3″, defective spots 4″, dog-ears 4″, adhesivetapes 6″ etc.) are not taken into account, as a result of which thechecking of the bank note is improved.

On the basis of the soiling of the bank note shown in representation 81,which is stored in the storage device of the control device 35, a finalassessment can be performed by the control device 35 so as to classifythe bank note as e.g. soiled, little soiled or not soiled. Such aclassification can be used for deciding as to whether the bank note e.g.is still fit for circulation.

In such an altered derivation it may be alternatively or additionallyprovided that the data of the optical sensor 31, which locally correlatewith the at least second property, are processed analogously, e.g. bymeans of a linear combination. With the altered derivation methods offuzzy logic can be employed alternatively or additionally. Here the dataof the optical sensor 31 can alternatively or additionally be linkedwith the data of other sensors, always linking data which relate to thesame place of the respective bank to be examined.

With the help of the described correlation of the different data therecan be achieved that the result of the checking of the bank notesgenerally is improved. This is achieved—as described—by the fact that inall cases of inaccuracy or insecurity when judging the state,authenticity, type of bank note etc., instead of solely with referenceto data of one sensor, by linking data of one or a plurality of othersensors it is achieved, that the quality of the assessment performed isimproved. By this means annoying manual re-processing, i. e. assessmentof the bank notes by an operator, becomes superfluous. In this way byusing the inventive method or inventive apparatus the rate of rejectionof bank notes when processed in a bank note processing machine can besubstantially reduced, as a result of which the re-processing is reducedrespectively and the throughput of bank notes is increased.

1. Method for checking bank notes, in which data from at least twodifferent measurings of the bank notes to be checked are evaluated,comprising the steps: a first property of the bank note to be checked isderived from the data of at least one first measuring, at least onesecond property of the bank note to be checked is derived from the dataof at least one second measuring, a correlation between first and atleast second property for the same places on the bank note to be checkedis determined, and the first property is derived once again, wherein atplaces of the bank note to be checked, for which a correlation betweenthe first and the at least second property was determined, an alteredderivation of the first property is effected from the data of the atleast first measuring.
 2. Method according to claim 1, wherein with thealtered derivation data of places with a correlation are not taken intoaccount.
 3. Method according to claim 1 wherein with the measurings datafor at least one side of the bank note to be checked are generated. 4.Method according to claim 3, wherein data for the complete side of thebank note to be checked are generated.
 5. Method according to claim 1,wherein the first property is a soiling of the bank notes to be checked.6. Method according to claim 1, wherein the first measuring is anoptical measuring.
 7. Method according to claim 1, wherein the secondproperty is a damage of the bank notes.
 8. Method according to claim 1,wherein the second measuring is an optical and/or acoustic measuring. 9.Apparatus for checking bank notes having at least two sensors, the dataof which are evaluated for the checking of bank notes by a controldevice, comprising the control device is arranged to derive a firstproperty of the bank note to be checked from the data of at least onefirst sensor, the control device is arranged to derive at least onesecond property of the bank note to be checked from the data of at leastone second sensor, the control device is arranged to determine acorrelation between first and at least second property for the sameplaces on the bank note to be checked, and the control device isarranged to once again derive the first property, wherein at places ofthe bank note to be checked, for which a correlation between the firstand the at least second property was determined, an altered derivationof the first property is effected from the data of the at least firstsensor.
 10. Apparatus according to claim 9, wherein with the alteredderivation the control device does not take into account data of the atleast first sensor relating to places with a correlation.
 11. Apparatusaccording to claim 9, wherein the sensors are arranged to generate datafor at least one side of the bank note to be checked.
 12. Apparatusaccording to claim 11, wherein the sensors are arranged to generate datafor the complete side of the bank note to be checked.
 13. Apparatusaccording to claim 9, wherein the first property is a soiling of thebank notes to be checked.
 14. Apparatus according to claim 9, whereinthe first sensor is an optical sensor.
 15. Apparatus according to claim9, wherein the second property is a damage of the bank notes to bechecked.
 16. Apparatus according to claim 9, wherein the second sensoris an optical and acoustic sensor, or either an optical or acousticsensor.